HLaB
Marie Attoinette Fan
Is it a 10 speed? If so then you can leave it until 0.75%, 11+ and best to replace at 0.5% wear.
Its an 11sp, I've not had a problem replacing it in the past at 0.75% touchwood 🤞 and its saw 38,000miles . Googling around says although some people (like me run to 0.75%) the ideal is 0.5% looks like I need a new chain checker. I already have a new chain I'll probably fit it at the weekend, more fettling fun to look forward too :-)